Although police sound repetitive when they categorize shooting after shooting as "gang related," in the case of that neighborhood, detectives tell the I-Team there is a leave-no-survivors war underway between two of Chicago's oldest and most ruthless street gangs.

Investigators Friday night are looking into whether the attack in Cornell Park is the latest in a volley of gang strikes the past few months around here. Detectives are checking if the 13 people shot and wounded could have specifically been payback for a gang ambush that took place earlier this month.

On a street corner three blocks away, a 22-year-old man and a 16-year-old boy were shot by a single gunman who walked up blasting.

That attack was part of a summer of violence in the Back of the Yards.

Police records show that in June seven were shot, three dead.

In July eight were shot, one dead.

August: Three shot, one dead.

And so far this month, 15 have been shot after Thursday night's attack that police say involved a military style assault rifle.

Friday Police Superintendent Garry McCarthy said the attack is a reminder that these guns need to be banned.

Coincidentally, in federal court Friday, we found a window to the gun pipelines that Chicago gangs depend on to stock their arsenals.

Twenty-three-year-old David "Big Man" Lewsibey of suburban South Holland, was convicted of supplying Chicago gangs with guns. Some of his products sold along a supply chain fashioned by Lewsibey, authorities say, are typical of the way gang bosses get their guns.

For more than 100 innocents in the Back of the Yards, this is the end game to the gang violence. A mural listing the names of those who have been caught in the crossfire the past 40 years, a wall with very little room left.

One of the names on that wall is Armando Sierra. He was 16 years old, a sophomore in high school, and not in a gang, when the Back of the Yards teenager was mistakenly killed by a gang bullet in 1989.

At his funeral one of his friends reflected on the violence of that day and asked, Can't somebody do something?"

Twenty-four years later, that is a question that has yet to be answered.